Tire inflation system

ABSTRACT

A tire inflation system including a drive mechanism having a rotational axis, a pump cavity positioned a radial distance away from the axis of rotation, and a force translator coupling the rotational axis to the pump cavity. The drive mechanism includes a cam comprising an arcuate bearing surface having a non-uniform curvature, the cam rotatable about the rotational axis, and an eccentric mass couple to the cam that offsets a center of mass of the drive mechanism from the rotational axis. The pump cavity is rotatably coupled to the cam, wherein the pump cavity includes an actuating element and a chamber. The force translator couples the arcuate bearing surface to the actuating element, wherein the force translator includes an axis having an arcuate position fixed to an arcuate position of the pump cavity.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/019,941, filed 6 Sep. 2013, which is a continuation of U.S. patentapplication Ser. No. 13/797,826, filed 12 Mar. 2013, which claims thebenefit of U.S. Provisional Application No. 61/613,406 filed 20 Mar.2012, U.S. Provisional Application No. 61/637,206 filed 23 Apr. 2012,and U.S. Provisional Application No. 61/672,223 filed 16 Jul. 2012,which are incorporated in its entirety by this reference.

This application is also related to U.S. application Ser. No. 13/469,007filed 10 May 2012, which is incorporated in its entirety by thisreference.

TECHNICAL FIELD

This invention relates generally to the pumping field, and morespecifically to a new and useful passive pump system in the pumpingfield.

BACKGROUND

Tires that are not optimally pressurized contribute to low fuelefficiency. These effects are particularly felt in the truckingindustry, where long distances and large loads amplify the effects of anunderinflated tire. However, it is often inconvenient and inefficientfor truck drivers to constantly stop, check, and inflate the vehicletires to the optimal pressure, leading to the persistence ofless-than-optimal fuel efficiency in most trucks. This problem has ledto several auto-inflating tire systems. Conventional auto-inflating tiresystems are either central or distributed, but each suffers from its ownset of drawbacks. Central inflation systems are complex and expensive,and require significant work for aftermarket installation (drillingthrough axles, tapping existing air lines, etc). Distributed systems aremounted at each wheel and can be less expensive, but the potential forreduced cost is typically at the expense of the continuous replacementof the device (which fails due to the harsh wheel environment).

Furthermore, passive pressurization systems can be desirable for tireinflation applications, as electrical energy storage mechanisms andprogramming can be eliminated from the system. However, conventionalpassive pressurization systems suffer from several problems. First,conventional passive pressurization systems using reciprocating pumpsoftentimes suffer from fatigue due to the high pressures and high numberof pumping cycles that are demanded. Second, passive pressurizationsystems can suffer from over-pressurization of the reservoir, whereinthe pressurization system continues to pump fluid into the reservoireven after the desired reservoir pressure is reached. Conventionalsystems typically resolve this problem with a relief valve, wherein therelief valve vents the reservoir contents into the ambient environmentwhen the reservoir pressure exceeds the desired pressure. This resultsin a loss of the already-pressurized fluid, resulting in additional pumpcycles to bring fluid at ambient pressure up to the desired pressure,thereby resulting in a shorter pump lifetime. Third, conventionaleccentric-mass driven pump systems, such as pendulum systems, experienceinstabilities when the rotating surface to which the eccentric mass iscoupled rotates near the excitation frequency for the given eccentricmass. More specifically, the eccentric mass rotates with the system atthis excitation frequency, resulting in radial oscillations that can bedetrimental to the overall system or to the rotating surface to whichthe pump system is coupled.

Thus, there is a need in the pumping field to create a new and usefulpump.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic representation of the pump system coupled to arotating surface.

FIGS. 2A and 2B are schematic representations of a variation of the pumpsystem in the recovered and compressed positions, respectively.

FIGS. 3A and 3B are cutaway views of a variation of the primary pump inthe compressed and recovered positions, respectively.

FIGS. 4A and 4B are sectional views of a variation of the pump systemwith the mass couple and with the mass couple cut away, respectively.

FIGS. 5A, 5B, and 5C are cutaway views of a variation of the pump systemin the recovery stroke, at the beginning of the compression stroke, andat the end of the compression stroke, respectively.

FIG. 6 is a perspective view of a variation of the pump system.

FIGS. 7A and 7B are schematic representations of a variation of the pumpsystem wherein the first reservoir pressure is equal to or below theambient pressure and wherein the first reservoir pressure is higher thanthe ambient pressure, respectively.

FIGS. 8A and 8B are schematic representations of a variation of thetorque stabilization mechanism in the pumping and non-pumping mode,respectively.

FIGS. 9A and 9B are schematic representations of a second variation ofthe torque stabilization mechanism in the pumping and non-pumping mode,respectively.

FIGS. 10A and 10B are schematic representations of a variation of thestabilizing mechanism in the pumping and non-pumping modes,respectively.

FIGS. 11A and 11B are schematic representations of a second variation ofthe stabilizing mechanism in the pumping and non-pumping modes,respectively.

FIGS. 12A and 12B are sectional views of a variation of the pressureregulation mechanism in the pumping and non-pumping modes, respectively.

FIGS. 13A and 13B are sectional views of a second variation of thepressure regulation mechanism in the pumping and non-pumping modes,respectively.

FIGS. 14A and 14B are sectional views of a third variation of thepressure regulation mechanism in the pumping and non-pumping modes,respectively.

FIGS. 15A and 15B are schematic flow diagrams of a variation of thepressure regulation mechanism in the pumping and non-pumping modes,respectively.

FIG. 16 is a cutaway view of the valve within the pressure regulationmechanism.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description of the preferred embodiments of the inventionis not intended to limit the invention to these preferred embodiments,but rather to enable any person skilled in the art to make and use thisinvention.

1. Pump System

As shown in FIG. 1, the pump system 10 includes a drive mechanism 100including a cam 120 coupled to an eccentric mass 140, a primary pump 200including a reciprocating element 220 and a pump body 240, and a forcetranslator 300 coupling the cam 120 to the reciprocating element 220.The pump system 10 functions to translate rotational motion into linearmotion. More preferably, the pump system 10 functions to translaterelative motion between the primary pump 200 and cam 120 into a pumpingforce, wherein the eccentric mass 140 retains the cam position relativeto a gravity vector while the primary pump 200 rotates relative to thecam 120 (e.g., with a rotating surface 20). The pump system 10preferably additionally functions to pressurize the pumped fluid. Theforce translator 300 preferably translates the relative motion betweenthe cam 120 and the primary pump 200 into the pumping force, which ispreferably applied against the reciprocating element 220. Morepreferably, the force translator 300 moves the reciprocating element 220through a compression stroke. The force translator 300 can additionallyfacilitate a recovery stroke (return stroke). However, the pump system10 can alternatively convert the relative motion into linear force,electrical energy (e.g., via piezoelectric sensors, motion through aninduced electric field, etc.), or any other suitable form of energy ormotion. The pump system 10 is preferably passively controlled, but canalternatively be actively controlled, wherein the system furtherincludes a power source, a plurality of sensors, and a controller thatcontrols valve operation based on sensor measurements.

The pump system 10 is preferably couplable to a surface that rotatesrelative to a gravity vector (rotating surface 20). The rotating surface20 is preferably a wheel of a vehicle, more preferably a truck, but canalternatively be any suitable rotating system, such as a windmill,waterwheel, or any other suitable rotating surface 20.

The pump system 10 preferably receives fluid from a first reservoir 400and pumps the fluid into a second reservoir 500. The fluid received fromthe first reservoir 400 preferably has a first pressure, and the fluidpumped into the second reservoir 500 preferably has a second pressurehigher than the first pressure but can alternatively have a pressuresubstantially similar to the first pressure. The fluid is preferably agas, more preferably ambient air, but can alternatively be any othersuitable gas, a liquid, or any other suitable fluid. The first reservoir400 is preferably the ambient environment, but can alternatively be afluid source (e.g., a fluid canister), an intermediary reservoir, or anyother suitable reservoir. When the first reservoir 400 is anintermediary reservoir, the first reservoir 400 preferably receivesfluid from a fluid source, such as the ambient environment or a fluidcanister. The second reservoir 500 is preferably a tire interior, butcan alternatively be any suitable reservoir. The pump system 10 canadditionally treat the pumped fluid, preferably prior to primary pumpingress but alternatively after primary pump egress. The fluid ispreferably treated (e.g., filtered) to remove debris, water, or anyother suitable undesired component of the fluid. The fluid is preferablytreated within the intermediary reservoir, when used. Alternatively, thefluid can be treated during primary pump ingress (e.g., wherein theinlet includes a filter) or at any suitable point within the fluid flowpath.

The drive mechanism 100 of the pump system 10 functions to generate thepumping force and to control the magnitude of the pumping force. Thepumping force (occluding force) is preferably a variable force appliedin a radial direction from a rotational axis of the drive mechanism 100,but can alternatively be a constant force, a force applied at anysuitable angle to the rotational axis, or any other suitable force. Thedrive mechanism 100 preferably includes the cam 120 and the eccentricmass 140. The drive mechanism 100 includes a rotational axis about whichthe drive mechanism 100 rotates relative to the primary pump 200(conversely, about which the primary pump 200 rotates relative to thedrive mechanism 100). The rotational axis of the drive mechanism 100 ispreferably the rotational axis of the cam 120, but can alternatively bethe rotational axis of the eccentric mass 140, the rotational axis aboutwhich the primary pump 200 rotates, or any other suitable rotationalaxis. The pump system 10 is preferably configured such that therotational axis of the drive mechanism 100 is substantially aligned withthe rotational axis of the rotating surface 20 when the pump system 10is coupled to the rotating surface 20, but the pump system 10 canalternatively be configured such that the rotational axis of the drivemechanism 100 is offset from the rotational axis of the rotating surface20. The drive mechanism 100 additionally includes a center of mass,determined from the mass and positions of the cam 120 and the eccentricmass 140. The eccentric mass 140 is preferably coupled to the cam 120such that the center of mass of the drive mechanism 100 is offset fromthe rotational axis of the drive mechanism 100.

The cam 120 of the drive mechanism 100 functions to control themagnitude of the pumping force. The cam 120 preferably functions toprovide a substantially constant torque against the reciprocatingelement 220 throughout the compression stroke, but can alternativelyprovide a variable torque against the reciprocating element 220throughout the compression or recovery strokes. The cam 120 preferablyincludes a bearing surface 122, wherein the profile of the bearingsurface 122 preferably controls the magnitude of the pumping forcethroughout the compression stroke. The bearing surface 122 is preferablycontinuous, but can alternatively be discontinuous. The bearing surface122 is preferably defined on the exterior of the cam 120 (exteriorbearing surface or outer bearing surface) but can alternatively bedefined within the interior of the cam 120 (interior bearing surface orinner bearing surface), as shown in FIG. 6, wherein the bearing surface122 defines a lumen within the cam 120. The bearing surface 122 ispreferably arcuate, and preferably has a non-uniform curvature (e.g., anoblong profile or a reniform profile, as shown in FIGS. 2 and 5,respectively). Alternatively, the bearing surface 122 can have a uniformcurvature (e.g., a circular profile), an angular profile, or any othersuitable profile. The bearing surface 122 preferably includes acompression portion and a recovery portion, corresponding to thecompression stroke and the recovery stroke of the primary pump 200,respectively. The compression portion is preferably continuous with therecovery section, but can alternatively be discontinuous. The bearingsurface 122 preferably has a first section 124 having a high curvature(preferably positive curvature or convex but alternatively negativecurvature or concave) adjacent a second section 126 having low curvature(e.g., substantially flat or having negative curvature compared to thefirst section 124). The bearing surface 122 preferably additionallyincludes a third section 128 connecting the first and second sections,wherein the third section 128 preferably provides a substantially smoothtransition between the first and second sections by having a lowcurvature adjacent the first section 124 and a high curvature adjacentthe second section 126. The compression portion preferably begins at theend of the second section 126 distal the first section 124, extendsalong the third section 128, and ends at the apex of the first section124, as shown in FIG. 5B. The compression portion is preferably convex(e.g., when the bearing surface 122 is an external bearing surface), butcan alternatively be concave. The apex of the first section 124preferably corresponds to the top of the compression stroke (compressedposition 222), as shown in FIG. 5C. The recovery portion preferablybegins at the apex of the first section 124, extends along the secondsection 126, and ends at the end of the second section 126 distal thefirst section 124, as shown in FIG. 5A. The recovery portion ispreferably substantially flat or concave (e.g., when the bearing surface122 is an external bearing surface 122), but can alternatively beconvex. The end of the second section 126 preferably corresponds to thebottom of the recovery stroke (recovered position 224). The slope of thecompression portion is preferably less than 30 degrees, but canalternatively have any suitable angle. When a roller is used as theforce translator 300, the curvature of the bearing surface 122 ispreferably at least three times larger than the roller curvature orroller diameter, but can alternatively be larger or smaller. However,the bearing surface 122 can have any suitable profile. The cam 120 ispreferably substantially planar with the bearing surface 122 definedalong the side of the cam 120, in a plane normal to the rotational axisof the cam 120 (e.g., normal the broad face of the cam 120). The bearingsurface 122 is preferably defined along the entirety of the cam side,but can alternatively be defined along a portion of the cam side. Thegenerated pump force is preferably directed radially outward of therotational axis, more preferably along a plane normal to the rotationalaxis. Alternatively, the cam 120 can have a rounded or otherwiseprofiled edge segment (transition between the cam broad face and the camside), wherein the bearing surface 122 can include the profiled edge.Alternatively, the arcuate surface is defined by a face of the camparallel to the rotational axis of the cam 120, wherein the generatedpump force can be directed at any suitable angle relative to therotational axis, varying from parallel to the rotational axis to normalto the rotational axis. The compression portion preferably encompassesthe majority of the cam profile, but can alternatively encompass halfthe cam profile or a small portion of the cam profile. In one variation,the compression portion covers 315 degrees of the cam profile, while therecovery portion covers 45 degrees of the cam profile. However, thecompression and recovery portions can cover any other suitableproportion of the cam profile.

The eccentric mass 140 (hanging mass) of the drive mechanism 100functions to offset the center of mass of the drive mechanism 100 fromthe rotational axis of the drive mechanism 100. This offset can functionto substantially retain the angular position of the drive mechanism 100relative to a gravity vector, thereby engendering relative motionbetween the drive mechanism 100 and the pump system components that arestatically coupled to the rotating surface 20 (that rotates relative tothe gravity vector). The eccentric mass 140 is preferably asubstantially homogenous piece, but can alternatively be heterogeneous.The eccentric mass 140 is preferably a substantially singular piece, butcan alternatively be made of multiple pieces or segments. In the lattervariation, the multiple pieces are preferably substantially similar inshape, angular and radial position, and mass, but can alternatively besubstantially different in profile, mass, angular position, or radialposition. The eccentric mass 140 is preferably a distributed mass (e.g.,extends along a substantial portion of an arc centered about therotational axis, as shown in FIG. 4B), but can alternatively be a pointmass. In certain applications, particularly those applications with highrotational speeds, the distributed mass can be preferable since thedistributed mass results in low oscillation frequencies, therebyresulting in a lower likelihood of eccentric mass excitation intospinning with the system in response to a linear oscillation introducedinto the system (e.g., bumps, system pulsation, etc.). The eccentricmass 140 is preferably curved, but can alternatively be substantiallyflat, angled, or have other suitable shape. The radius of the eccentricmass curvature is preferably maximized, such that the eccentric masstraces an arcuate section of the pump system perimeter. However, theeccentric mass 140 can have any other suitable curvature. The eccentricmass 140 preferably extends at least 90 degrees about the rotationalaxis of the drive mechanism 100, more preferably 180 degrees about therotational axis, but can extend more or less than 180 degrees about therotational axis. The eccentric mass 140 preferably has substantiallymore mass than the cam 120, but can alternatively have a substantiallysimilar mass or a smaller mass. The eccentric mass 140 preferablyimparts 2 in-lb (0.225 Nm) of torque on the cam 120, but canalternatively impart more or less torque.

The eccentric mass 140 is preferably a separate piece from the cam 120,and is preferably coupled to the cam 120 by a mass couple 142.Alternatively, the eccentric mass 140 can be incorporated into the cam120, wherein the eccentric mass 140 is incorporated along the perimeterof the cam 120, incorporated into a half of the cam 120, or incorporatedalong any other suitable portion of the cam 120. The eccentric mass 140can be statically coupled to the cam 120 or rotatably coupled to the cam120. In the variation wherein the eccentric mass 140 is staticallycoupled to the cam 120, the eccentric mass 140 can be coupled to the cam120 at the rotational axis of the cam 120, at the rotational axis of thedrive mechanism 100, offset from the rotational axis of the cam 120, orat any other suitable portion of the cam 120. The eccentric mass 140 canbe permanently connected to the cam 120. Alternatively, the eccentricmass 140 can be transiently connected (removably coupled) to the cam120, wherein the eccentric mass 140 can be operable between a pumpingmode wherein the eccentric mass 140 is coupled to the cam 120 and anon-pumping mode wherein the eccentric mass 140 is disconnected from thecam 120. The mass couple 142 preferably has a high moment of inertia,but can alternatively have a low moment of inertia. The mass couple 142is preferably a disk (as shown in FIG. 4A), but can alternatively be alever arm, plate, or any other suitable connection. The mass couple 142preferably couples to the broad face of the cam 120, but canalternatively couple to the edge of the cam 120, along the exteriorbearing surface of the cam 120, to the interior bearing surface of thecam 120, to an axle extending from of the cam 120 (wherein the cam 120can be statically fixed to or rotatably mounted to the axle), or to anyother suitable portion of the cam 120. The mass couple 142 can couple tothe cam 120 by friction, by a transient coupling mechanism (e.g.,complimentary electric or permanent magnets located on the cam 120 andmass couple 142, a piston, a pin and groove mechanism, etc.), bybearings, or by any other suitable coupling means. When the mass couple142 couples to the cam 120 by a transient coupling mechanism, the masscouple 142 is preferably operable between a coupled mode, wherein themass couple 142 connects the eccentric mass 140 to the cam 120, and adecoupled mode, wherein the mass couple 142 disconnects the eccentricmass 140 from the cam 120. The mass couple 142 can additionally functionas a shutoff mechanism, wherein the mass couple 142 is switched from thecoupled mode to the decoupled mode in response to the detection of ashutoff event (e.g., the reservoir pressure reaching a thresholdpressure). In one variation, the mass couple 142 is a disk locatedwithin the lumen defined by an interior bearing surface of the cam 120,wherein the disk can rotate relative to the interior bearing surface inthe decoupled mode and is coupled to the interior bearing surface by afriction element in the coupled mode. In another variation, the masscouple 142 is rotatably mounted on an axle extending from the cam 120 bybearings, wherein the mass couple 142 can be statically coupled to thecam 120 by one or more sets of magnets or pistons extending from theadjacent broad faces of the cam 120 and mass couple 142.

The primary pump 200 of the pump system 10 functions to pressurize afluid with the pumping force generated between the cam 120 and thereciprocating element 220. The primary pump 200 is preferably a positivedisplacement pump including an actuating element and a pump cavity, andis more preferably a reciprocating pump, wherein the primary pump 200includes a reciprocating element 220 and a pump body 240. The primarypump 200 preferably includes a lumen defined between the reciprocatingelement 220 and the pump body 240, wherein the lumen is preferablysubstantially fluid impermeable. The primary pump 200 is preferablyrotatably coupled to the rotational axis of the drive mechanism 100. Theprimary pump 200 is preferably positioned a radial distance away fromthe rotational axis of the drive mechanism 100, wherein the radialposition of the primary pump 200 is preferably fixed, but canalternatively be adjustable. More preferably, the primary pump 200 ispreferably statically mounted to a housing (wherein the housing isstatically coupled to the rotating surface 20) but can alternatively betransiently mounted to the housing (adjustably mounted). In operation,the primary pump 200 preferably rotates about the rotational axis.Throughout the rotation, the variable bearing surface profile preferablyapplies a variable force to the reciprocating element 220 as thedistance between the bearing surface 122 and the pump body bottomvaries. The primary pump 200 preferably includes an actuation axis,wherein the reciprocating element 220 preferably travels along theactuation axis through the compression stroke. The reciprocating element220 can additionally travel along the same actuation axis during thereturn stroke. The primary pump 200 is preferably oriented such that theactuation axis is substantially normal to the rotational axis, but canalternatively be positioned such that the actuation axis is at anysuitable angle to the rotational axis. The primary pump 200 and cam 120preferably share a common plane, wherein the pumping force is preferablytransmitted along the common plane, but can alternatively besubstantially offset. The system preferably includes one primary pump200, and more preferably includes two pump cavities. However, the pumpsystem 10 can include any suitable number of pump cavities. When thepump system 10 includes multiple pump cavities, the pump cavities arepreferably substantially evenly distributed about the rotational axis(e.g., have substantially similar distances between the respectiveangular positions), but can alternatively be unevenly distributed. Thepump cavities preferably have substantially similar radial positionsrelative to the rotational axis, but can alternatively have differentradial positions. The pump cavities can be substantially different(e.g., with different lumen volumes, different actuation areas, etc.) orcan be substantially similar.

The reciprocating element 220 of the primary pump 200 functions toreceive the pumping force from the cam 120 and translate within thelumen, actuating relative to the pump body 240. This actuationpreferably creates a variable pressure within the lumen. Thereciprocating element 220 is preferably operable between a compressedposition 222 and a recovered position 224, as shown in FIGS. 3A and 3B,respectively. In the compressed position 222, a portion of thereciprocating element 220 (e.g., the center) is preferably proximal thepump body bottom. In the recovered position 224, the portion of thereciprocating element 220 is preferably distal the pump body bottom, andis preferably proximal the pump body opening. The reciprocating element220 preferably travels along a compression stroke to transition from therecovered position 224 to the compressed position 222, and travels alonga recovery stroke to transition from the compressed position 222 to therecovered position 224. The reciprocating element 220 can additionallybe positioned at a pressurized position, wherein the reciprocatingelement 220 is located at a second position distal the pump body bottom,wherein the second position is further from the pump body bottom thanthe recovered position 224. The reciprocating element 220 is preferablyat the pressurized position when the force provided by the lumenpressure exceeds the force provided by the cam 120 on the reciprocatingelement 220.

The reciprocating element 220 preferably translates along an actuationaxis within the primary pump 200 throughout the compression stroke, andcan additionally translate along the actuation axis throughout therecovery stroke. The reciprocating element 220 preferably includes anactuating area that provides the pressurization force. The actuatingarea is preferably the surface area of a broad face of the reciprocatingelement 220, more preferably the surface area of the broad face proximalthe lumen but alternatively any other suitable broad face.Alternatively, the actuating area can be the surface area of a sectionof the reciprocating element 220 that translates between the compressedposition 222 and the recovered position 224 (e.g., the center portion).

The reciprocating element 220 preferably forms a fluid impermeable sealwith the pump body 240, more preferably with the walls defining the pumpbody opening, such that the reciprocating element 220 substantiallyseals the pump body opening. The reciprocating element 220 can be sealedto the pump body 240 by a retention mechanism. The retention mechanismis preferably a clamp that applies a compressive force against thereciprocating element edge and the pump body wall, but can alternativelybe screws or bolts through the reciprocating element edge, adhesivebetween the reciprocating element 220 and the pump body wall or over thereciprocating element 220 and the pump body wall, or any other suitableretention mechanism. The reciprocating element 220 can also be sealedagainst the pump body wall by melting the interface between thereciprocating element 220 and pump body wall, or by any other suitablemeans of sealing the reciprocating element 220 against the pump bodywall.

The reciprocating element 220 is preferably a flexible diaphragm, butcan alternatively be a substantially rigid piston, a piston coupled tothe diaphragm, or any other suitable element that actuates in responseto the pumping force. The diaphragm is preferably a rolling diaphragm(e.g., with a rolled perimeter, wherein the diaphragm is preferablycoupled to the pump body 240 with the extra material distal the lumen)but can also be a flat diaphragm, a domed diaphragm (preferably coupledto the pump body 240 with the apex distal the lumen, but alternativelycoupled to the pump body 240 with the apex proximal the lumen), or anyother suitable diaphragm.

The pump body 240 of the primary pump 200 functions to cooperativelycompress a fluid with the reciprocating element 220. The pump body 240is preferably substantially rigid, but can alternatively be flexible.The pump body 240 is preferably an open pump body with a closed end,wherein the pump body 240 preferably includes a closed end (bottom),walls extending from the closed end, and an opening opposing the closedend. However, the pump body 240 can alternatively have two open ends orany other suitable configuration. The closed end is preferablysubstantially flat, but can alternatively be curved or have any othersuitable geometry. The walls are preferably substantially flat, but canalternatively be curved or have any other suitable geometry. The wallspreferably join with the closed end at an angle, more preferably at aright angle, but the transition between the walls and the closed end canalternatively be substantially smooth (e.g., have a bell-shaped orparaboloid longitudinal cross section). The closed end is preferablysubstantially parallel to the opening defined by the walls, but canalternatively be oriented at an angle relative to the opening. The pumpbody 240 can be a groove defined in an arcuate or prismatic piece (e.g.,in a longitudinal or lateral direction), a cylinder, a prism, or anyother suitable shape. The pump body 240 preferably has a substantiallysymmetrical lateral cross section (e.g., circular, ovular, orrectangular cross section, etc.), but can alternatively have anasymmetrical cross section. The pump body 240 is preferably orientedwithin the pump system 10 such that the closed end is substantiallynormal to a radial vector extending from the rotational axis of thedrive mechanism 100 (e.g., the normal vector from the closed end issubstantially parallel to the radial vector), but can alternatively beoriented with the closed end at an angle to the radial vector. The pumpbody 240 is preferably oriented with the opening proximal and the closedend distal the rotational axis, particularly when the primary pump 200rotates about the cam exterior, but can alternatively be oriented withthe opening distal and the closed end proximal the rotational axis,particularly when the primary pump 200 rotates about the cam interior,or oriented in any other suitable position relative to the rotationalaxis.

The primary pump 200 can additionally include a return element 260 thatfunctions to return the reciprocating element 220 to the recoveredposition 224. The return element 260 preferably provides a recoveryforce that is less than the compression force provided by the thirdsection 128 of the cam 120, but larger than the force applied by the cam120 in the second section 126. The recovery force is preferably providedin a direction substantially parallel to a radial vector extending fromthe rotational axis of the drive mechanism 100, but can alternatively beprovided in any suitable direction. The return element 260 is preferablylocated on the pump body 240 side of the reciprocating element 220(distal the cam 120 across the reciprocating element 220), wherein thereturn element 260 preferably pushes the reciprocating element 220 fromthe compressed position 222, through the recovery stroke, and to therecovered position 224. Alternatively, the return element 260 can belocated on the cam side of the reciprocating element (distal the pumpbody 240 across the reciprocating element 220), wherein the returnelement 260 pulls the reciprocating element 220 back to the recoveredposition 224 from the compressed position 222. The return element 260 ispreferably coupled to the perimeter of the reciprocating element 220 orto a component (e.g., a brace) coupled to the reciprocating element 220and extending past the pump body walls, but can alternatively be coupledto the body of the reciprocating element 220 (e.g., to the sectionactuating between the compressed position 222 and the recovered position224). The return element 260 is preferably coupled to the reciprocatingelement 220 external the pump body 240, but can alternatively be coupledto the reciprocating element 220 within the pump body 240. The returnelement 260 is preferably a spring, but can also include the intrinsicproperties of the actuation element (e.g., the elasticity of thediaphragm) or any other suitable return element 260.

The primary pump 200 preferably additionally includes one or more inletsthat facilitate fluid ingress into the lumen from the first reservoir400 and one or more outlets that facilitate fluid egress from the lumento the second reservoir 500. Alternatively, the primary pump 200 caninclude one fluid manifold that functions as both the inlet and outlet,wherein said fluid manifold is fluidly connected to and selectivelypermits fluid flow from the first and second reservoirs. The inlet andoutlet are preferably defined through the walls of the pump body 240,but can alternatively be defined through the reciprocating element 220,through the junction between the pump body 240 and the reciprocatingelement 220, or defined in any other suitable portion of the primarypump 200. The inlet and outlet are preferably located on opposing walls,but can alternatively be adjacent on the same wall, be located on theclosed end, or be located in any other suitable position.

The inlet and outlet of the pump 200 preferably include inlet and outletvalves that control fluid flow through the respective fluid channels.The valves are preferably passive valves, but can alternatively beactive valves controlled by a controller based on system measurementsmade by sensors. The valves are preferably one-way valves, but canalternatively be two-way valves, or any other suitable valve. The valvesare preferably each operable in an open mode and a closed mode, andpreferably have a low threshold pressure at which the valve switchesfrom the closed mode to the open mode. The inlet valve located withinthe inlet is preferably configured to control fluid ingress into theprimary pump 200, and prevents fluid egress out of the primary pump 200.The inlet valve is preferably in the open mode to permit fluid ingresswhen the lumen pressure is lower than or equal to the pressure withinthe first reservoir 400. Alternatively, the inlet valve can be in theopen mode when the lumen pressure is negative. The inlet valve ispreferably in the closed mode when the lumen pressure is higher than orequal to the pressure within the first reservoir 400. The outlet valvelocated within the outlet is preferably configured to control fluidegress from the primary pump 200, and prevents fluid ingress into theprimary pump 200. The outlet valve is preferably in the open mode topermit fluid egress when the lumen pressure exceeds the pressure withinthe second reservoir 500 and the outlet valve threshold pressure. Theoutlet valve is preferably in the closed mode when the lumen pressure islower than or equal to the pressure within the second reservoir 500.

The force translator 300 of the pump system 10 functions to actuate thereciprocating element 220 through the compression stroke as the primarypump 200 rotates about the rotational axis, and can additionallyfunction to translate the reciprocating element 220 through the recoverystroke. The force translator 300 preferably includes an axis having anarcuate position that is fixed relative to an arcuate position of theprimary pump 200 (the angular position of the force translator 300 axisabout the rotational axis is preferably fixed relative to the angularposition of the primary pump 200). More preferably, the force translator300 or a portion thereof has an angular position fixed to andsubstantially similar to the angular position of the primary pump 200about the rotational axis, such that the force translator 300 travelswith the primary pump 200 about the rotational axis.

In a first variation of the force translator 300, the force translator300 travels along the arcuate bearing surface 122 of the cam 120, Theforce translator 300 preferably maintains a substantially constantdistance between the arcuate bearing surface 122 and the reciprocatingelement 220, such that the force translator 300 applies a variable forceagainst the reciprocating element 220 as the force translator 300travels along the variable curvature of the arcuate bearing surface 122of the cam 120. The force translator 300 is preferably substantiallyrigid, and preferably has substantially fixed dimensions (e.g.,diameter) that remain substantially constant throughout force translatormotion relative to the cam 120. The force translator 300 is preferably aroller or bearing, wherein the axis that is fixed to the primary pumpangular position is preferably the rotational axis of the roller. Theforce translator 300 is preferably in non-slip contact with the arcuatebearing surface 122, but can alternatively slide along the arcuatebearing surface 122. The force translator 300 is preferably rotatablycoupled to the reciprocating element 220, but can alternatively beotherwise coupled to the reciprocating element 220. When thereciprocating element 220 is a piston, the reciprocating element 220preferably rotatably connects to the roller at the rotational axis ofthe roller, but can connect to the roller with a semi-circular cup thatcups the roller, or through any other suitable coupling mechanism. Whenthe reciprocating element 220 is a diaphragm, the reciprocating element220 can directly contact the diaphragm, couple to the diaphragm througha piston, or couple to the diaphragm in any other suitable manner.

In another variation of the force translator 300, the force translator300 is rotatably coupled to the cam 120 at a fixed position on the cam120 and rotatably coupled to a fixed position on the reciprocatingelement 220. The force translator 300 is preferably rotatably coupled tothe reciprocating element 220 (e.g., at a piston), but can alternativelybe slidably coupled to the reciprocating element 220 or otherwisecoupled to the reciprocating element 220. In this variation, the forcetranslator 300 preferably translates the varying distance between therespective fixed ends into the variable occluding force. The forcetranslator 300 is preferably a linkage with two or more links, but canalternatively be any suitable force translator 300.

However, the force translator 300 can alternatively be any suitablemechanism that translates cam rotation relative to the primary pump 200into a variable occluding force against the reciprocating element 220.

The pump system 10 preferably additionally includes a housing thatfunctions to couple the pump system components to the rotating surface20. The housing is preferably configured to removably statically coupleto the rotating surface 20, but can otherwise couple to the rotatingsurface 20. More preferably, the housing is configured to mount (e.g.,bolt, screw, etc.) to the hub of a tire, but can alternatively mount tothe rim, axle, or any other suitable component of a tire. The housing ispreferably rotatably coupled to the drive mechanism 100 and ispreferably statically coupled to the pump body 240 of the primary pump200, such that the primary pump 200 rotates with the housing. Thehousing can additionally function to mechanically protect the pumpsystem components, wherein the housing preferably substantially enclosesthe pump system components. The housing is preferably substantiallyrigid, but can alternatively be substantially flexible. The housing ispreferably substantially fluid impermeable, but can alternatively bepermeable to fluid. In one variation of the pump system 10, the housingfunctions as the first reservoir 400, wherein the primary pump 200 inletis fluidly connected to and draws fluid from the housing interior. Inthis variation, the housing can include an inlet manifold fluidlyconnecting the housing interior with the ambient environment. As shownin FIGS. 7A and 7B, the inlet manifold preferably includes awater-selective membrane that preferentially permits gas flowtherethrough (e.g., the gas flow rate through the water-selectivemembrane is higher than the water flow rate through the water-selectivemembrane). The water-selective membrane is preferably a GORE™ membrane,but can alternatively be any other suitable membrane. The inlet manifoldcan alternatively include an inlet valve that controls fluid flow intothe housing interior, but can alternatively not include any valves. Theinlet valve is preferably a passive one-way valve operable between anopen mode in response to the housing interior pressure falling below orbeing equal to the ambient pressure and a closed mode in response to thehousing interior pressure exceeding the ambient pressure. However, theinlet valve can be an active valve, a two-way valve, or any othersuitable valve.

2. Relief Valve

The pump system 10 can additionally include a relief valve 700 whichfunctions to leak air from the interior of the second reservoir 500(e.g. tire interior) of the into the pump system 10, more preferablyinto the housing of the pump system 10 (e.g. the first reservoir 400),but can alternatively leak air from the second reservoir 500 to theambient environment. Leaking air through the relief valve 700 can conferseveral benefits. First, leaking air through the relief valve 700 canprevent overpressurization of the second reservoir 500. Second, leakingair through the relief valve 700 can allow the pump system 10 directlymeasure the internal pressure of the second reservoir 500. Third,leaking air through the relief valve 700 into the housing (firstreservoir 400) effectively recycles the already-pumped air, reducing theamount of air treatment (e.g. desiccation) required. The relief valve700 preferably connects to the second reservoir interior through theSchraeder valve of the second reservoir 500, but can otherwise fluidlyconnect to the second reservoir 500. The relief valve 700 preferablyoperates between an open mode wherein air flow through the relief valve700 is permitted, and a closed mode wherein air flow through the reliefvalve is prevented. The relief valve preferably includes an openthreshold pressure, and is preferably a fail closed relief valve. Theshutoff threshold is preferably set to leak second reservoir pressure ata rate substantially close to the flow rate of the pump (e.g. 10 cubicinches/minute), but can alternatively leak at a rate substantially closeto the normal second reservoir leakage rate (e.g., 1-3 psi per month),but can alternatively leak second reservoir pressure at a higher orlower rate. The relief valve 700 is preferably a normally-closed reliefvalve, but can alternatively be a normally-open relief valve that isheld closed, or any other suitable valve. The relief valve 700 ispreferably passive, but can alternatively be active. The relief valve700 is preferably a check relief valve, but can alternatively be anyother suitable relief valve 700. Examples of relief valves that can beused include a duckbill relief valve, a pilot-operated relief valve, aball relief valve, a poppet relief valve, and a diaphragm relief valve.Alternatively, any other suitable relief valve can be used.

A measurement element functions to monitor an operational parameter anddisplay a measurement indicative of internal second reservoir pressure.The measurement element is preferably located within the body of thepump system 10, but can be partially or wholly external the pump system10. The measurement element is preferably fluidly coupled to the reliefvalve 700, and preferably measures a parameter of the fluid that flowsthrough the relief valve 700. The measurement element is preferablypassive, but in alternative embodiments the measurement element can beactive.

The measurement element preferably includes a sensor and a display. Thesensor preferably measures the operational parameter, and can be apressure sensor, a flow rate sensor, a temperature sensor, or any othersuitable sensor. The sensor can be mechanical or digital (e.g., generatea voltage/current, be powered, or leverage a voltage/current formeasurements). The display is preferably passive, and can be a dialindicator, a ruler, or any other suitable gauge. However, the displaycan be active (e.g., powered, such as a digital display), wherein thedisplayed value can be calculated by a controller.

In a first variation, the measurement element includes a measurementreservoir and a pressure gauge. The reservoir is fluidly coupled to therelief valve 700, such that air leaks from the second reservoir interiorinto the measurement reservoir when the valve opens. The measurementreservoir is preferably substantially small, such that the measurementreservoir pressure equilibrates with the second reservoir pressure evenwith the low air leakage rate permitted by the relief valve. However,the measurement reservoir can alternatively be any suitable size. Themeasurement reservoir is preferably a plenum, but can alternatively be atube, channel, or any other suitable reservoir. The pressure gauge ispreferably coupled to the reservoir and measures the pressure of thereservoir interior. The pressure measured is preferably the gaugepressure, but may alternatively be the differential pressure (e.g.,between the reservoir interior and the second reservoir inflation systemexterior/ambient) or the absolute pressure. The display portion of thepressure gauge is preferably located on the external surface of the pumpsystem 10, more preferably parallel to the face of the wheel to whichthe pump system 10 is mounted.

In a second variation, the measurement element includes a mass air flowmeter coupled to a display. The flow meter preferably measures andfluidly couples to the inflator side of the relief valve (e.g.,downstream from the relief valve), but can alternatively measure theflow into the relief valve (e.g., second reservoir 500 side flow) orflow through the relief valve body, wherein a portion of the flow meteris located within the relief valve. In this variation, the downstreamside of the relief valve is preferably held at an approximately knownpressure that is substantially higher than ambient, but slightly lowerthan the expected second reservoir pressure. For example, the reliefvalve can be coupled to a downstream reservoir that includes a reliefvalve with a threshold opening pressure slightly lower than the expectedsecond reservoir pressure, such that the downstream pressure will alwaysbe approximately the threshold opening pressure. In another exampleembodiment, the relief valve can be coupled to the second reservoirinflator reservoir holding the air to be pumped into the secondreservoir 500. The flow meter preferably produces a voltage or currentindicative of the air flow rate, wherein the voltage/current is fed intoa controller, converted into a pressure measurement by the controller,and displayed as a pressure readout. Alternatively, the flow meter canbe passive and measure the flow rate mechanically, wherein the positionof a gauge or indicator is converted into a pressure readout. The airflow meter can be a vane meter sensor, a hot wire sensor, a coldwiresensor, a Karman vortex sensor, a membrane sensor, a laminar flowelement, a turbine flow meter, a rotary piston, or any other suitableflow meter. The display is preferably a digital display, but canalternatively be an analog display.

However, any other suitable relief valve can be included in the pumpsystem 10 to facilitate second reservoir pressure regulation.

3. Torque Stabilization Mechanism

The pump system 10 can additionally include a torque stabilizationmechanism 600 that compensates for the back force applied by the primarypump 200 to the cam 120 at the beginning of the recovery stroke.Compensation of the back force can be desirable as the back force canprovide a radial force on the cam 120, which in turn can be transmittedto the eccentric mass 140, thereby disrupting the system. The torquestabilization mechanism 600 is preferably located on the cam 120, butcan alternatively be located on the force translator 300 (e.g., have anadjustable dimension that changes in response to the applied force), onthe primary pump 200, or on any other suitable pump system component.

In one variation of the pump system 10, the cam profile functions as thetorque stabilization mechanism 600, wherein the low curvature of thesecond segment accommodates for the back force.

In another variation of the pump system 10, the mass couple 142functions as the torque stabilization mechanism 600, wherein the masscouple 142 is operable in the coupled mode during the compression stroke(through the third section 128 up to the apex of the second section 126)and operable in the decoupled mode during the recovery stroke. In oneexample, as shown in FIGS. 8A and 8B, the torque stabilization mechanism600 includes a profiled channel 610 defined between the interior bearingsurface of the cam and the mass couple 142 (e.g., wherein the masscouple 142 is a disk) by the interior bearing surface. The profiledchannel 610 preferably includes a low clearance section 612 extending toa high clearance section 614, wherein the clearance is the distancebetween the mass couple surface and the interior bearing surface. Theapex of the high clearance section is preferably substantially radiallyaligned with the first section 124, more preferably with the apex of thefirst section 124, but can alternatively be aligned with the beginningof the second section 126, slightly before the apex of the first section124, or aligned with any other suitable portion of the cam 120. Thebeginning of the low clearance section is preferably radially alignedwithin the arc defined by the third section 128, but can alternativelybe aligned with any suitable portion of the cam 120. The torquestabilization mechanism 600 preferably additionally includes a mobileelement 620 located within the profiled channel 610 that couples anddecouples the mass couple 142 with the interior bearing surface. Themobile element preferably couples the mass couple 142 with the interiorbearing surface with friction, but can alternatively be a ratchetingmechanism or any other suitable mechanism. The mobile element preferablyhas a dimension substantially equivalent to the distance between masscouple surface and the interior bearing surface at the low clearancesection. The mobile element is preferably wedged in the low clearancesection when the eccentric mass 140 is in the coupled mode, wherein themobile element retains the position of the mass couple 142 relative tothe interior bearing surface. The mobile element is preferably locatedin the high clearance section when the eccentric mass 140 is in thedecoupled mode, wherein the mobile element is substantially free fromthe mass surface and/or interior bearing surface and permits relativemotion between the mass couple 142 and the interior bearing surface. Themobile element is preferably a roller, but can alternatively be acylinder or any other suitable mobile element. In operation, as theprimary pump 200 reaches the apex of the first section 124 (compressedposition 222), the reciprocating element 220 exerts a radial back forceon the force translator 300, pushing the cam 120 radially away from theprimary pump 200. Furthermore, as this point is reached, the angularspeed of the cam 120 relative to the primary pump 200 slows down. Thisradial motion, coupled with the slower angular cam speed, frees themobile element from the low clearance section (wherein the mobileelement is still travelling at the faster angular speed), and causes themobile element to travel with the high clearance section as the primarypump 200 travels over the second section 126 of the arcuate surface, asshown in FIG. 8B. The angular cam speed preferably increases as theprimary pump 200 travels over the second section 126, but canalternatively stay substantially constant or slow down. At the end ofthe second section 126, the angular cam speed is preferably decreaseddue to the increased contact force between the cam 120, force translator300, and primary pump 200. This decreased angular speed preferablycauses the mobile element to wedge into the low clearance section, asshown in FIG. 8A.

In another variation, the torque stabilization mechanism 600 includes agroove 630 defined within the cam 120 and a pin 640 extending from themass couple 142 into the groove. The groove preferably functions toaccommodate for the radial back force by turning the linear back forceinto a rapid rotation of the cam 120 (relative to the primary pump 200)through the first section 124. The pin is preferably operable between acoupled position (shown in FIG. 9A) and a decoupled position (shown inFIG. 9B) within the groove. The groove is preferably defined through thecam body in a normal direction to the cam broad face, but canalternatively be defined any suitable portion of the cam body. Thegroove is preferably aligned with the second section 126 of the arcuatebearing surface 122, but can be defined in any other suitable portion ofthe cam 120. The groove preferably traces an arc, but can alternativelybe substantially linear, serpentine, or have any other suitable shape.In operation, the back pressure applied by the primary pump 200 on thecam 120 forces the pin from the coupled position to the decoupledposition, effectively rotating the cam 120 relative to the eccentricmass 140. When the primary pump 200 reaches the end of the secondsection 126, the force applied by the cam 120 on the primary pump 200preferably transitions the pin back to the coupled position.

However, any other suitable torque stabilization mechanism 600 thataccommodates for the radial force applied by the pressurized primarypump 200 on the cam 120 can be used.

4. Passive Pressure Regulation Mechanism

The pump system 10 can additionally include a passive pressureregulation mechanism 800 that preferably functions to passively ceasepressurization of the reservoir when a threshold reservoir pressure isreached. This is preferably accomplished by passively ceasing primarypump pumping. The passive pressure regulation mechanism 800 preferablyceases pumping by ceasing force application to the reciprocating element220, wherein force application can be ceased by decoupling the forcetranslator 300 from the cam 120, decoupling the primary pump 200 fromthe cam 120, decoupling the force translator 300 from the primary pump200, or eliminating the relative motion between the primary pump 200 andthe cam 120, an example of which is shown in FIGS. 15A and 15B. Thepassive pressure regulation mechanism 800 of the pump system 10preferably includes a secondary pump 820 including pump body 240 and anactuating mechanism 840, and additionally includes a regulation valve860 having an opening and a closing threshold pressure. Alternatively,the passive pressure regulation mechanism 800 can include a regulationvalve 860 and the primary pump 200. The passive pressure regulationmechanism 800 is preferably fluidly connected to the second reservoir500, wherein the regulation valve 860 selectively controls fluid flowinto the secondary pump 820 based on the pressure of the secondreservoir 500.

The secondary pump 820 is preferably a reciprocating pump substantiallysimilar to that described above, wherein the actuating mechanism 840 isthe reciprocating element. The secondary pump 820 is more preferably apiston pump but can alternatively be a diaphragm pump. The secondarypump 820 can alternatively be any other suitable positive displacementpump. The pressure regulation mechanism 800 is preferably operable in apressurized mode and a depressurized mode. The pressurized mode ispreferably achieved when the reservoir pressure exceeds the thresholdpressure. More preferably, the pressurized mode is achieved when thereservoir pressure exceeds the opening threshold pressure of the valve860. In the pressurized mode, the valve 860 is preferably in an openposition and permits fluid flow from the reservoir into the pump body240, wherein the pressure of the ingressed fluid places the actuatingmechanism 840 in the pressurized position. In the pressurized position,the actuating mechanism 840 preferably actuates or couples against thedrive mechanism 100, force translator 300, or primary pump 200 to ceasepumping force application to the primary pump 200. In the depressurizedmode, the valve 860 is preferably in a closed position and preventsfluid flow from the reservoir into the pump body 240, wherein a returnmechanism places the actuating mechanism 840 in a depressurizedposition, wherein the depressurized position is preferably the recoveredposition 224 but can alternatively be the compressed position 222 or anyother suitable position therebetween. The pump system 10 preferablyincludes at least one pressure regulation mechanism 800, but canalternatively include any suitable number of pressure regulationmechanisms.

The position of the pressure regulation mechanism 800, more preferablythe position of the pump body 240, is preferably statically coupled tothe primary pump position, but can alternatively be moveably connectedto the primary pump 200 position. The angular position of the pressureregulation mechanism 800 is preferably maintained relative to theprimary pump position, but the radial or linear distance canalternatively be maintained. The actuation axis of the pressureregulation mechanism 800 is preferably in the same plane as theactuation axis of the primary pump 200, but can alternatively be indifferent planes, perpendicular to the actuation axis of the primarypump 200, or arranged in any other suitable manner. The pressureregulation mechanism 800 is preferably arranged relative to the primarypump 200 such that the direction of the compression stroke of thepressure regulation mechanism 800 differs from the direction of thecompression stroke of the primary pump 200. The direction of thecompression stroke of the pressure regulation mechanism 800 directlyopposes the direction of the compression stroke of the primary pump 200(e.g., the closed end of the pump cavity is distal the closed end of thepump body 240, and the actuating element is proximal the reciprocatingelement 220, wherein the actuation axes are aligned or in parallel), butcan alternatively be at an angle to the direction of the compressionstroke of the primary pump 200. Alternatively, the pressure regulationmechanism 800 can be arranged such that the compression stroke of thepressure regulation mechanism 800 and the compression stroke of thepressure regulation mechanism 800 have substantially the same direction(e.g., the actuation axes are aligned or in parallel).

In one variation of the pressure regulation mechanism 800, the actuatingmechanism 840 decouples the primary pump 200 or a primary pump componentfrom drive mechanism 100 when in the pressurized position, and permitsthe primary pump 200 to couple with the drive mechanism 100 when in thedepressurized position (as shown in FIGS. 12A and 12B). The actuatingmechanism 840 preferably decouples the force translator 300 from thedrive mechanism 100, but alternatively decouples the reciprocatingelement 220 or the entirety of the primary pump 200 from the drivemechanism 100. The actuating mechanism 840 preferably moves the primarypump component along the actuation axis of the primary pump 200, awayfrom the cam 120, when transitioning from the depressurized position tothe pressurized position. However, the actuating mechanism 840 can movethe primary pump component at an angle to the actuation axis of theprimary pump 200, away from the cam 120 (e.g., in a perpendiculardirection). The actuating mechanism 840 preferably translates theprimary pump component within the plane encompassing the actuation axisor the pump body 240, but can alternatively translate the primary pumpcomponent out of said plane. The force exerted on the actuatingmechanism 840 by the return element 260 of the secondary pump 820preferably couples the primary pump component with the drive mechanism100 while returning the actuating mechanism 840 to the depressurizedposition, but the pump system 10 can alternatively include a secondreturn element 260 that couples the primary pump component to the drivemechanism 100 (e.g., a spring biased such that the spring opposes thedirection that the actuating mechanism 840 moves the primary pumpcomponent, etc.). The second return element 260 preferably returns theprimary pump component contact with the drive mechanism 100 when thedecoupling force of the actuating mechanism falls below the return forceprovided by the second return element.

A portion of the actuating mechanism 840 is preferably staticallycoupled to a portion of the primary pump 200, wherein actuatingmechanism actuation results in a positional change of the primary pump200 or a primary pump component. More preferably, actuating mechanismactuation preferably selectively couples and decouples the primary pump200 from the drive mechanism 100 when the actuating mechanism 840 is inthe depressurized and pressurized positions, respectively. The actuatingmechanism 840 is statically coupled to the force translator 300, but canalternatively be statically coupled to the reciprocating element 220,statically coupled to the primary pump 200 as a whole, or staticallycoupled to any other suitable primary pump component. The actuatingmechanism 840 is preferably statically coupled to the primary pumpcomponent by a frame 880, but can alternatively be coupled by thehousing encapsulating the pump system 10 or by any other suitablecoupling mechanism. The frame 880 can be aligned within the planeencompassing the actuation axis of the primary pump 200, within theplane encompassing the actuation axis of the pressure regulationmechanism 800, extend out of either of said two planes, or be otherwiseoriented relative to the pump system 10. In a specific example, theforce translator 300 is a roller, wherein the actuating mechanism 840 iscoupled to the rotational axis of the roller by a frame 880 aligned witha plane encompassing both the actuation axis of the pressure regulationmechanism 800 and the actuation axis of the primary pump 200, whereinthe pressure regulation mechanism 800 and primary pump 200 preferablyshare a common plane. Alternatively, the actuating mechanism 840transiently couples to the primary pump component when in thepressurized position, and is retracted away from the primary pumpcomponent when in the depressurized position.

In another variation of the pressure regulation mechanism 800, theactuating mechanism 840 decouples the force translator 300 from primarypump 200 in the pressurized position, and permits force translator 300coupling with the primary pump 200 when in the depressurized position.The actuating mechanism 840 preferably connects to and moves the forcetranslator linear position relative to the drive mechanism 100 when inthe pressurized position, but can alternatively connect to and move theprimary pump linear position relative to the force translator 300 anddrive mechanism 100. The actuating mechanism 840 preferably moves theforce translator 300 out of the common plane shared by the primary pump200 and the drive mechanism 100, but can alternatively move the forcetranslator 300 out of line with the actuation axis (e.g., perpendicular,within the common plane). The actuating mechanism 840 can be staticallycoupled to the force translator 300 or primary pump 200 by a frame 880,a weld, adhesive, or any other suitable coupling mechanism.Alternatively, the actuating mechanism 840 can be transiently coupled tothe force translator 300 or primary pump 200, wherein the actuatingmechanism 840 can be a piston or rod that transiently couples to theforce translator 300 or primary pump 200 through a coupling feature(e.g., a groove) or friction.

In another variation of the pressure regulation mechanism 800, theactuating mechanism 840 ceases force generation. In one alternative, thepressure regulation mechanism 800 statically couples the angularposition of the drive mechanism 100 to the primary pump 200, ceasingforce generation by eliminating the relative motion between the drivemechanism 100 and the primary pump 200 (as shown in FIGS. 13A and 13B).For example, the actuating mechanism 840 can statically couple theangular position of the cam 120 with the angular position of the primarypump 200 in the pressurized position, and decouple the angular positionof the cam 120 from the angular position of the primary pump 200 in thedepressurized position. In a specific example, the actuating mechanism840 is a rod that couples to the cam broad face by friction. In anotherspecific example, the actuating mechanism 840 is a rod that extends intoa groove in the cam broad face (e.g., the broad face proximal thehousing or distal the housing) when in the pressurized position, and isretracted from the groove when in the depressurized position. In anotherspecific example, the actuating mechanism 840 statically couples to thearcuate bearing surface 122 of the cam 120. However, other mechanisms oftransiently retaining the cam angular position can be used. In anotherexample, the actuating mechanism 840 can statically couple the angularposition of the eccentric mass 140 with the angular position of theprimary pump 200. In a specific example, the actuating mechanism 840 caninclude a rod that couples to the broad face of the eccentric mass 140or to the mass couple 142 by friction. In another specific example, theactuating mechanism 840 is a rod that extends into a groove in theeccentric mass face when in the pressurized position and is retractedfrom the groove when in the depressurized position. However, othermechanisms of transiently retaining the eccentric mass angular positioncan be envisioned. In another example, the pump body 240 of the primarypump 200 can be statically coupled to the drive mechanism 100, such thatrelative motion between the reciprocating element 220 and the pump body240 is ceased (e.g., when a linear or rotary actuator is used). Inanother alternative, the pressure regulation mechanism 800 decouples theforce generator from the drive interface of the drive mechanism 100. Forexample, when the cam 120 and eccentric mass 140 are transiently coupledby a transient coupling mechanism, the actuating mechanism 840 canactuate the cam 120, eccentric mass 140, or coupling mechanism todecouple the cam 120 from the eccentric mass 140. In one specificexample as shown in FIGS. 14A and 14B, the cam 120 is coupled to theeccentric mass 140 along the respective broad faces by a ring of magnets842 encircling the rotational axis, and the actuating mechanism 840extends through a hole in the cam 120 (or eccentric mass 140) and pushesagainst the broad face of the eccentric mass 140 (or cam 120) todecouple the eccentric mass 140 from the cam 120. The actuatingmechanism 840 can be statically coupled to the force translator 300 orprimary pump 200 by a frame 880 or other coupling mechanism.Alternatively, the actuating mechanism 840 can be transiently coupled tothe force translator 300 or primary pump 200, wherein the actuatingmechanism 840 can be a piston or rod that couples to the forcetranslator 300 or primary pump 200.

In another variation of the pressure regulation mechanism, the pressureregulation mechanism 800 switches the primary pump 200 from the pumpingmode and a locked mode. The primary pump 200 preferably pumps fluid inthe pumping mode and does not pump fluid in the locked mode. Morepreferably, components of the pump system 10 are held in static relationrelative to each other in the locked mode, such that the reciprocatingelement 220 is held substantially static. The primary pump 200 ispreferably placed in the locked mode when the pressure of the secondreservoir 500 exceeds the opening threshold pressure of the valve 860,and is preferably placed in the pumping mode when the pressure of thesecond reservoir 500 falls below the closing threshold pressure of thevalve 860. More specifically, when the pressure of the second reservoir500 exceeds the opening threshold pressure, the valve 860 opens,allowing pressurized air to flow from the second reservoir 500 into thecompression volume of the primary pump 200, substantially retaining thereciprocating element 220 in the initial position of the compressionstroke (e.g., in the recovered position). In this manner, the increasedforce of pressurized air on the reciprocating element 220 substantiallyopposes cam motion when the reciprocating element 220 is located at thesecond section 126 of the cam profile, but can alternatively oradditionally oppose cam motion when the reciprocating element 220 islocated at the first section 124 or third section 128 of the camprofile. Since the cam 120 is preferably configured to only apply asmall force to the reciprocating element 220 at the second section 126,the cam 120 cannot overcome the large back force applied by the backflowon the reciprocating element 220. These aspects of the pump system 10effectively cease pumping within the primary pump 200. The force appliedby the backflow prevents cam movement relative to the primary pump 200,causing the cam 120 and subsequently, the eccentric mass 140, to rotatewith the pump system 10. When the pump system 10 includes multiplepumps, all the pumps are preferably flooded with pressurized air.Alternatively, a single pump can be flooded with pressurized air,alternating pumps can be flooded with pressurized air, or any othersuitable subset of the pumps can be flooded to cease pumping.

However, any other suitable means of ceasing pumping force applicationto the reciprocating element 220 can be used.

The valve 860 of the pressure regulation mechanism 800 functions toselectively permit fluid flow into the pump body 240 of the secondarypump 820. The valve 860 preferably has an opening threshold pressuresubstantially equal to the desired reservoir pressure (e.g., the upperlimit of a desired reservoir pressure range), and can additionally havea closing threshold pressure under, over, or equal to the desiredreservoir pressure (e.g., the lower limit of a desired reservoirpressure range). The valve 860 can additionally function as a timer, andhave a pumping resumption pressure at which primary pump pumping isresumed. The pumping resumption pressure is preferably determined by theratio of the first and second pressurization areas within the valve.Alternatively, the pressure regulation mechanism 800 can include a timerthat functions to delay the resumption of pumping after the closingthreshold pressure is reached. The valve 860 is preferably located inthe fluid manifold fluidly connecting the second reservoir 500 with thepump body 240. However, the valve 860 can be located within the secondreservoir 500 or within the pump body inlet. The opening thresholdpressure is preferably a higher pressure than the closing thresholdpressure, wherein the opening and closing threshold pressures arepreferably determined by the return force applied by the return element.The valve state is preferably determined by the pressure within thesecond reservoir 500. The pumping resumption pressure is preferablylower than the closing threshold pressure, but can alternatively behigher than the closing threshold pressure or be any suitable pressure.The valve 860 is preferably operable between an open mode when thepressure of the second reservoir 500 exceeds an opening thresholdpressure, wherein the valve 860 permits fluid flow from the secondreservoir 500 into the pump body 240, and a closed mode when thepressure of the second reservoir 500 is below the closing threshold.pressure, wherein the valve 860 prevents fluid flow from the secondreservoir 500 into the pump body 240. Pumping by the primary pump 200 ispreferably resumed when the pressure within the second pump 820 fallsbelow the pumping resumption pressure, but can alternatively be resumedwhen the reservoir pressure falls below the closing threshold. The valve860 is preferably a snap-action valve, but can alternatively be anyother suitable valve 860. The valve 860 is preferably passive but canalternatively be active. The valve 860 preferably includes a valvemember 864 that seats within a valve body 862, and can additionallyinclude a return mechanism (e.g., a spring) that biases the valve member864 against the valve body 862. The valve member 864 and valve body 862can be different materials (e.g., to compensate for material expansiondue to temperature changes), or can be made of the same material ormaterials with similar expansion coefficients.

In one variation of the pressure regulation mechanism 800, thesnap-action valve 860 is substantially similar to the valve described inU.S. application Ser. No. 13/469,007 filed 10 May 2012.

In another variation of the pressure regulation mechanism 800, as shownin FIG. 16, the snap-action valve 860 includes a valve body 862, a valvemember 864, a spring 865, a first volume 866, a second volume 867, areservoir channel 868, and a manifold channel 869. The spring or returnelement 865, biases the valve body 862 against the valve member 864. Thespring constant of the spring is preferably selected based on thedesired reservoir pressure (threshold pressure or cracking pressure) andthe desired valve operating characteristics. The first volume ispreferably defined between the valve body 862 and valve member 864, andpreferably has a first pressurization area normal to a direction ofspring force application. The second volume is preferably also definedbetween the valve body 862 and valve member 864, and preferably has asecond pressurization area normal to the direction of spring forceapplication. The second. reservoir channel preferably fluidly connectsthe first volume with the second reservoir 500. The manifold channel ispreferably defined through the valve body 862, and is preferably fluidlyconnected to the pressure regulation. mechanism 800. The manifoldchannel is preferably defined along the axis of return forceapplication, opposing the return element 260 across the valve member864, but can alternatively be defined, in any other suitable location.The valve 860 can additionally include a timing channel fluidly couplingthe second volume to an ambient environment, wherein the timing channelhas a cross section selected based on a desired leak rate. The ratio ofthe first pressurization area to the second pressurization area ispreferably selected based on the desired amount of time the valve 860takes to recover the closed position, but can alternatively be anysuitable ratio. The combined volume of the first and second volumes arepreferably substantially insignificant relative to the second reservoirvolume. The valve 860 is preferably operable between an open positionand closed position. In the open position, the valve body 862 and valvemember 864 cooperatively define a connection channel fluidly connectingthe first volume with the second volume, wherein the valve member 864 islocated distal the valve body 862. The open position is preferablyachieved when a pressure force generated by a pressure within the firstvolume overcomes the spring force applied by the spring on the valvebody 862. In the closed mode, the valve member 864 and valve body 862cooperatively seal the connection channel and the valve member 864substantially seals the manifold channel, wherein the valve member 864seats against the valve body 862. The closed mode is preferably achievedwhen the pressure force is lower than the applied spring force. In onealternative of the valve 860, the valve member 864 has a symmetric crosssection including a stem configured to fit within the manifold channel,a first overhang extending from the stem, and a second overhangextending from the first overhang. The valve body 862 includes a crosssection complimentary to the valve member cross section, including afirst step defining the manifold channel, a second step extending fromthe first step, and walls extending from the second step. The firstvolume is preferably defined between the second step and the secondoverhang, the second volume is preferably defined between the first stepand the first overhang, and the connection channel is preferably definedbetween a transition from the first overhang to the second overhang anda transition between the first step to the second step. The valve 860can further include gaskets bordering and cooperatively defining thefirst and second volumes. In one alternative of the valve 860, the valve860 includes a first gasket located within the connection channel thatforms a first substantially fluid impermeable seal with the valve member864 in the closed mode and a second fluid impermeable seal definedbetween the second overhang and the walls. The valve 860 canadditionally include a gasket within the manifold channel that forms afluid impermeable seal with the stem when the valve 860 is in the closedmode (e.g., to cooperatively define the second volume), and permitsfluid flow therethrough when the valve 860 is in the open mode.

5. Stabilizing Mechanism

The pump system 10 can additionally include a stabilizing mechanism 900that functions to reduce rotational surface imbalance when the eccentricmass 140 becomes excited (e.g., begins spinning) when the pump system 10rotates at or near the excitation frequency of the eccentric mass 140.The stabilizing mechanism 900 is preferably the eccentric mass 140,wherein the eccentric mass 140 is collectively formed from multiplesections. However, the stabilizing mechanism 900 can alternatively beany other suitable stabilizing mechanism 900. When the eccentric mass140 begins to spin, the composite sections of the eccentric massseparate. This is particularly useful when system oscillations cause theeccentric mass 140 (and positioning mechanism) to spin about the shaft;the centrifugal forces cause the sections of the split eccentric mass140 to separate and be evenly distributed about the axis of systemrotation, as shown in FIGS. 10A and 10B. Not only does this have theeffect of dynamically balancing the system and/or rotating surface 20,but the even distribution of the eccentric mass 140 within the systemalso halts system pumping. The latter effect can allow the eccentricmass 140 to additionally function as a control mechanism, wherein theeccentric mass resonant frequency can be tailored such that pumping isceased when a predetermined rotation speed or vibration frequency isreached. The multiple sections are preferably each positioned the sameradial distance away from the rotational axis (the eccentric mass 140 isradially divided into multiple sections, wherein the multiple sectionshave different angular positions), but can alternatively be positionedat different radial distances (e.g., wherein the multiple sections havesubstantially similar angular positions, etc.). The multiple sectionspreferably share a common plane, wherein the common plane is preferablysubstantially parallel to the rotational surface. The multiple sectionscan collectively form an arc, centered about the rotational axis, thatintersects the common plane (e.g., the multiple sections are adjacentalong an arc), form a block that intersects the common plane, orcollectively form any other suitable structure. Alternatively, themultiple sections can be stacked along the thicknesses of the sections,wherein the section thicknesses are preferably parallel to therotational axis. The multiple sections preferably have substantially thesame mass, but can alternatively have different masses. The center ofmass for each eccentric mass section is preferably offset from the masscouple connection point for each eccentric mass section, and ispreferably arranged proximal an adjacent eccentric mass section. Inoperation, the eccentric mass sections separate until the centers ofmass of the eccentric mass sections oppose each other across the axis ofrotation.

When the eccentric mass 140 is cooperatively formed by multiplesections, the mass couple 142 preferably also includes multiplesections, wherein each mass couple section statically couples to aneccentric mass section. The mass couple sections are preferablyrotatably coupled to the cam 120, but can alternatively be staticallycoupled to the cam 120. Each mass couple section is preferably rotatablycoupled to the remaining mass couple sections, but can alternatively bestatically coupled to one or more of the remaining mass couple sections.In one variation as shown in FIGS. 11A and 11B, the end of each masscouple section opposing the eccentric mass section is rotatably coupledto the housing. The angular positions of mass couple section ends arepreferably static relative to the housing, wherein the mass couplesection ends are preferably equally distributed about the axis ofrotation. In another variation, the end of the each mass couple sectionopposing the eccentric mass section includes a bearing, wherein thebearing is slidably engaged within a circumferential groove staticallycoupled to the cam 120 and encircling the rotational axis. When therotation frequency of the rotating surface 20 is below or above theexcitation frequency for the cooperatively defined eccentric mass 140,the centrifugal force of the rotation preferably retains the eccentricmass sections (and mass couple sections) in substantially adjacentpositions. When the rotation frequency of the rotating surface 20 is atthe excitation frequency, the centrifugal force preferably causes thebearings to slide within the groove, distributing the multiple eccentricmass sections substantially equally about the rotational axis. Thebearings and/or the eccentric mass sections can each additionallyinclude magnets, disposed in repulsive relation to adjacent magnets,which facilitate eccentric mass separation in response to the receipt ofa system oscillation. In another variation, the mass couple sectionsrotatably couple along the longitudinal axis of an axle extending fromthe cam 120 (e.g., mass couple sections are stacked along the axle). Inanother variation, one mass couple section is statically connected tothe cam 120 while the remaining mass couple sections are rotatablyconnected to the cam 120. However, the mass couple sections can beotherwise connected to the cam 120.

When the mass couple 142 couples to the cam 120 at the rotational axis,the mass couple 142 is preferably operable between the coupled mode,wherein the mass couple 142 connects the eccentric mass 140 to the cam120, and the decoupled mode, wherein the mass couple 142 disconnects theeccentric mass 140 from the cam 120. In one variation, the mass couple142 is a disk located within the lumen defined by an interior bearingsurface of the cam 120, wherein the disk can rotate relative to theinterior bearing surface in the decoupled mode and is coupled to theinterior bearing surface by a friction element in the coupled mode. Themass couple sections are preferably rotatably coupled to the disk, butcan alternatively be disk sections (e.g., concentric circles, arcuatepieces, etc.). The friction element can be a high-friction coating alongthe interior bearing surface, a high-friction coating along the masscouple 142 exterior, a roller or wedge, or any other suitable elementcapable of providing friction between the interior bearing surface andthe mass couple 142. The friction element is preferably selected suchthat the cooperative centrifugal force of the eccentric mass 140 in thecoupled mode applies sufficient force to the mass couple 142 such thatthe friction between the mass couple 142 and the interior bearingsurface retains the mass couple position relative to the cam 120. Thefriction element is preferably selected such that the cooperativecentrifugal force of the eccentric mass sections in a separated ordecoupled mode does not provide enough force to interface friction toretain the mass couple position relative to the cam 120, therebyallowing free mass couple rotation. In another variation, the masscouple 142 is rotatably mounted on an axle extending from the cam 120 bybearings, wherein the mass couple 142 can be statically coupled to thecam 120 by one or more sets of magnets or pistons extending from theadjacent broad faces of the cam 120 and mass couple 142. However, thestatic mass couple connection to the cam 120 to achieve the coupled modecan be selectively controlled by any other suitable passive or activemeans.

The eccentric mass 140 can additionally include a connection mechanismthat functions to couple the multiple sections together. The connectionmechanism is preferably located on the interfaces of adjacent sections,but can alternatively be located within the section bodies, at theinterfaces of adjacent mass couple sections, or at any other suitablelocation. The coupling force of the connection mechanism is preferablyselected such that it is substantially equal to or lower than theangular separation force experienced by the individual eccentric masssections when the system is rotating at the excitation frequency.However, the coupling force can have any other suitable magnitude. Theconnection mechanism can be a mechanical connection (e.g., adhesive,clips, Velcro, etc.) with a separation force substantially equivalent tothe coupling force, a magnetic connection wherein adjacent eccentricmass or mass couple sections include complimentary magnets, or any othersuitable mechanism that can selectively connect adjacent eccentric masssections together.

In one alternative, the eccentric mass 140 is collectively formed by afirst and a second section (e.g., the eccentric mass 140 is dividedradially into two sections), wherein the first section is a reflectedduplication of the second section. In operation, the first and secondsections are preferably diametrically opposed and spin about the axis ofrotation of the positioning mechanism when the system vibration reachesthe resonance frequency of the eccentric mass 140. In a secondalternative, the eccentric mass 140 is collectively formed by a first,second, and third section with substantially the same mass, wherein thefirst, second and third sections are preferably substantially evenlydistributed about the rotational axis when the system rotational speedreaches the resonance frequency of the eccentric mass 140. However, theeccentric mass 140 can be formed from any number of constituent sectionsin any suitable configuration. Alternatively, the stabilizing mechanism900 can be any other suitable mechanism.

The pump system 10 can additionally include a damping mechanism thatfunctions to minimize oscillations of the eccentric mass 140 within thesystem. Oscillations of the eccentric mass 140 can result in eccentricmass excitation, wherein the eccentric mass 140 spins within the systeminstead of remaining substantially static relative to a gravity vector.Oscillations can arise from irregularities in the rolling surface (e.g.,the road), dynamic unbalance (e.g., due to wheel mass distribution.),the pumping pulse (e.g., when the pumping pulse occurs at a frequencythat excites the mass), or can arise from any suitable mechanism thatcan generate oscillations of the eccentric mass 140.

In a first variation, the damping mechanism includes Dynabeads or otherdynamic balancing mechanisms located within an internal channelencircling the rotational axis. In a second variation, the dampingmechanism is a torsional mass-spring system, wherein the resonantvibration period of the mass-spring system is preferably matched to thegravitationally induced resonant frequency of the eccentric mass 140oscillation. The torsion spring is preferably coupled to the cam 120such that the eccentric mass 140 oscillations cause an inertialtransfer, which excites the torsional mass-spring system into resonanceat a phase shift that is 180 degrees out of phase with the oscillationsof the eccentric mass 140. The torsion spring is preferably coupledbetween the torsional mass and the cam 120, but can alternatively bepositioned between the cam 120 and the mass couple 142, or in anysuitable position.

6. Example Pump System

In one embodiment of the pump system 10, as shown in FIGS. 12A and 12B,the pump system 10 includes a first and a second reciprocating pump (200a and 200 b, respectively), a drive mechanism 100, a first and a secondforce translator (300 a and 300 b, respectively) connected to the firstand second reciprocating pumps, respectfully, the first and second forcetranslators having a first and second axis in fixed relation,respectively, a fluid manifold 202 fluidly connecting the secondreciprocating pump to a reservoir 500, and a valve 860 located withinthe fluid manifold 202. The first pump 200 a preferably includes anoutlet fluidly connected to the second reservoir 500, wherein the firstpump 200 a pumps fluid to and pressurizes the second reservoir 500. Thefirst pump 200 a preferably includes an inlet fluidly connected to afluid source, wherein the fluid source can be the ambient environment,the housing (e.g., wherein the housing encloses desiccated air), or anyother suitable fluid source. The second pump 200 b can additionallyinclude an inlet (separate from that coupled to the fluid manifold 202but alternatively the same one) and outlet fluidly connected to thefluid source and reservoir, respectively, wherein the second pump 200 bcan pump fluid to and pressurize the second reservoir 500.Alternatively, the inlet and outlet of the second pump 200 b can befluidly connected to the fluid source and to the inlet of the first pump200, respectively, thereby forming a two-stage pump. In thisalternative, fluid is pressurized to a first pressure within the secondpump 200 b and pressurized to a second pressure at the first pump 200 a.The first and second reciprocating pumps preferably include a first andsecond pump body (240 a and 240 b), respectively, and a first and secondreciprocating element (220 a and 220 b), respectively. The first andsecond reciprocating pumps preferably share a common plane (e.g., therespective actuating axes share a common plane), but can alternativelybe located in different planes. The first and second reciprocating pumpsare preferably equally radially distributed about the drive mechanism100, more preferably equally distributed about the rotational axis ofthe drive mechanism 100. However, the pumps can be otherwisedistributed. The positions of the first and second pump bodies arepreferably statically fixed by a housing or other component, wherein thehousing statically couples the pump system 10 to a rotating surface 20and can additionally enclose the pump system 10. The first and secondreciprocating pumps preferably oppose each other, wherein the closed endof the first pump body 240 a is distal the closed end of the second pumpbody 240 b and the first reciprocating element 220 a is proximal thesecond reciprocating element 220 b. The first reciprocating element 220a preferably has a first pressurization area (area that receives orgenerates a pressure force) and the second reciprocating element 220 bpreferably has a second pressurization area. The first pressurizationarea is preferably smaller than the second pressurization area, but canalternatively be larger or smaller. The drive mechanism 100 preferablyincludes a rotational axis 102, a cam 120 rotatable about the rotationalaxis, the cam 120 having a bearing surface 122, and an eccentric mass140 coupled to the cam 120 that offsets the center of mass of the drivemechanism 100 from the rotational axis. The first force translator 300 ais preferably couplable to the bearing surface 122 of the cam 120 innon-slip contact, and is preferably statically connected to thereciprocating element 220 of the first pump along an axis (e.g.,rotational axis). The second force translator 300 b preferably slipsrelative to the bearing surface 122 of the cam 120, but canalternatively couple in non-slip contact with the bearing surface 122.The second force translator 300 b is preferably statically connected tothe reciprocating element 220 of the second pump along an axis (e.g.,rotational axis). The first and second force translators can each be aroller, a piston, a piston coupled to the roller at the rotational axis,or any other suitable force translator. The positions of the first andsecond force translators are preferably statically retained by a frame880, but can alternatively be retained by any other suitable mechanism.The frame 880 preferably encloses the drive mechanism 100, such that thedrive mechanism 100 is located within the area bounded by the frame 880.However, the frame 880 can be otherwise arranged relative to the drivemechanism 100. The frame 880 is preferably located in the common planeshared by the first and second pumps, but can alternatively be locatedin a separate plane (e.g., extend normal to said plane and extend alonga second plane parallel to the first). In operation, a radial or linearposition of the frame 880 preferably shifts from a first position to asecond position relative to a point on the drive mechanism 100 (e.g.,rotational axis) when second reciprocating element 220 moves from thedepressurized position to the pressurized position, respectively. Thedistance between the first position and the second position ispreferably substantially similar to the distance between thedepressurized position and the pressurized position, but canalternatively be larger (e.g., wherein the frame 880 amplifies thechange in reciprocating element position) or smaller. Frame 880 movementpreferably results in simultaneous first and second force translatormovement, coupling the first force translator 300 a to the drivemechanism 100 in the first position and decoupling the first forcetranslator 300 a from the drive mechanism 100 in the frame's secondposition. Alternatively, frame movement can result in first and secondreciprocating pump movement relative to the drive mechanism 100, whereinthe frame 880 statically connects the positions of the first and secondpump bodies. However, the force translators can be otherwise connectedand disconnected to the drive mechanism 100. The frame 880 canadditionally include features, such as arcuate grooves on the surface ofthe frame 880 proximal the drive mechanism 100, which facilitate secondforce translator 300 b slip relative to the bearing surface 122. Thefluid manifold preferably fluidly connects the second reservoir 500 toan inlet of the second pump, but can additionally fluidly connect thesecond reservoir 500 to an inlet of the first pump. In the latteralternative, the valve is preferably located upstream of the junctionbetween the three fluid connections or within the junction. In thislatter alternative, valve opening simultaneously floods both lumens ofthe first and second reciprocating pumps. Because the secondreciprocating pump preferably has a larger pressurization area than thefirst reciprocating pump, the second reciprocating pump preferablyexerts a linear (e.g., radial) decoupling force on the frame 880, whichis transferred by the frame 880 into a shift in the position of thefirst force translator 300 a away from the drive mechanism 100,effectively decoupling the first force translator 300 a from the drivemechanism 100.

As a person skilled in the art will recognize from the previous detaileddescription and from the figures and claims, modifications and changescan be made to the preferred embodiments of the invention withoutdeparting from the scope of this invention defined in the followingclaims.

I claim:
 1. A tire inflation system comprising: a drive mechanism havinga rotational axis, the drive mechanism comprising: a) a cam comprisingan arcuate bearing surface having a non-uniform curvature, the camrotatable about the rotational axis; and b) an eccentric mass couple tothe cam that offsets a center of mass of the drive mechanism from therotational axis; a pump cavity positioned a radial distance away fromthe axis of rotation and rotatably coupled to the cam, the pump cavitycomprising an actuating element and a chamber; and a force translatorcoupling the arcuate bearing surface to the actuating element, the forcetranslator comprising an axis having an arcuate position fixed to anarcuate position of the pump cavity.
 2. The tire inflation system ofclaim 1, wherein the force translator comprises a rotation axis, whereinan arcuate position of the rotation axis is fixed relative to the pumpcavity.
 3. The tire inflation system of claim 2, wherein the forcetranslator comprises a roller in non-slip contact with the arcuatebearing surface of the cam.
 4. The tire inflation system of claim 3,wherein the force translator further comprises a piston rotatablyconnected to the rotation axis, wherein the actuating element comprisesthe piston.
 5. The tire inflation system of claim 4, wherein theactuating element comprises a diaphragm.
 6. The tire inflation system ofclaim 1, wherein the arcuate bearing surface has a first section havinghigh curvature adjacent a second section having low curvature.
 7. Thetire inflation system of claim 6, wherein the arcuate bearing surfacefurther comprises a third section between the first and second sections,the third section having curvature varying from a low curvature proximalthe second section to a high curvature proximal the first section. 8.The tire inflation system of claim 7, wherein the arcuate bearingsurface comprises an outer perimeter of the cam.
 9. The tire inflationsystem of claim 6, further comprising a torque stabilization mechanismconfigured to accommodate a force of the actuating element on the camduring a return stroke.
 10. The tire inflation system of claim 9,wherein the drive mechanism further comprises a mass couple operable in:a coupled mode wherein the mass couple connects the eccentric mass tothe cam; and a decoupled mode wherein the mass couple disconnects theeccentric mass from the cam.
 11. The tire inflation system of claim 10,wherein the mass couple couples to an interior bearing surface of thecam, wherein: in the coupled mode, the mass couple is statically coupledto an interior bearing surface of the cam, and in the decoupled mode,the mass couple is rotatably coupled to the interior bearing surface.12. The tire inflation system of claim 10, wherein the torquestabilizing mechanism comprises a profiled channel defined between theinterior bearing surface and the mass couple, the profiled channelhaving a low clearance section and a high clearance section, the torquestabilizing mechanism further comprising a mobile element having adimension substantially equal to the low clearance section and smallerthan the high clearance section, the mobile element located within theprofiled channel, wherein the torque stabilizing mechanism switches themass couple between: the coupled mode, wherein the mobile element islocated in the low clearance section and retains a position of the masscouple with the interior bearing surface; and the decoupled mode,wherein the mobile element is located in the high clearance section andpermits relative motion between the mass couple and the interior bearingsurface.
 13. The tire inflation system of claim 12, wherein the highclearance section is substantially radially aligned with the firstsection of the arcuate bearing surface.
 14. The tire inflation system ofclaim 1, further comprising a second pump cavity comprising a secondactuating element and a second chamber; and a second force translatorcoupling the arcuate bearing surface to the second actuating element,the second force translator comprising a second axis having a secondarcuate position fixed to an arcuate position of the second pump cavity.15. The tire inflation system of claim 14, further comprising a passivepressure regulation system comprising a passive valve fluidly connectedto a reservoir, the reservoir fluidly connected to an outlet of thefirst pump cavity, the passive valve having a opening threshold pressureand a closing threshold pressure lower than the opening thresholdpressure, the passive valve operable between: an open mode in responseto a reservoir pressure exceeding the opening threshold pressure,wherein the passive valve permits fluid flow from the reservoir; and aclosed mode in response to a reservoir pressure falling below theclosing threshold pressure, wherein the passive valve prevents fluidflow from the reservoir.
 16. The tire inflation system of claim 15,wherein the passive pressure regulation system further comprises a fluidmanifold fluidly connecting the first pump cavity, the second pumpcavity, and a reservoir fluidly coupled to the first and second pumpcavities, wherein the passive valve is located within the fluidmanifold, wherein: in the open mode, the passive valve permits fluidflow from the reservoir to the first and second pump cavities; and inthe closed mode, the passive valve prevents fluid flow from thereservoir to the first and second pump cavities.
 17. The tire inflationsystem of claim 16, wherein the second actuating element comprises alarger actuating area than the first actuating element.
 18. The tireinflation system of claim 17, wherein an inlet to the first pump cavityis fluidly connected to an outlet from the second pump cavity.
 19. Thetire inflation system of claim 16, further comprising a frame staticallyconnecting the first axis with the second axis, the frame operablebetween: a pumping position wherein the frame places the first forcetranslator in non-slip contact with the arcuate bearing surface, whereinthe second force translator is connected to the arcuate bearing surfacethrough the first force translator and the frame; and a non-pumpingposition, wherein the frame disconnects the first force translator fromthe arcuate bearing surface and slidably couples the second forcetranslator to the arcuate bearing surface.
 20. The tire inflation systemof claim 19, wherein a frame center is located at a first radialposition in the pumping position and at a second radial position in thenon-pumping position, wherein the first radial position is differentfrom the second radial position.
 21. The tire inflation system of claim19, wherein the second pump cavity is operable between: a compressedposition wherein the second actuating element is substantially proximala closed end of the second chamber; a recovered position wherein thesecond actuating element is located at a first position distal a closedend of the second chamber; and a pressurized position wherein the secondactuating element is located at a second position distal the chamber,the second position further from the chamber than the first position,wherein the second actuating element is placed in the pressurizedposition in response to a pressure of the reservoir surpassing theopening pressure, wherein the frame is placed in the non-pumpingposition when the second pump cavity is placed in the pressurizedposition.
 22. The tire inflation system of claim 1, further comprising ahousing coupled to the drive mechanism and the pump cavity, the housingconfigured to statically mount to a rotating surface, the rotatingsurface configured to rotate relative to a gravity vector.
 23. The tireinflation system of claim 22, wherein the housing encloses the drivemechanism, the pump cavity, and the force translator, the housingfurther comprising a water-selective membrane fluidly connecting anambient environment to a housing interior, wherein an inlet of the pumpcavity is fluidly connected to the housing interior.
 24. The tireinflation system of claim 23, wherein comprising a relief valve operablebetween an open state wherein the relief valve fluidly connects areservoir to the housing interior, the reservoir fluidly connected to anoutlet of the pump cavity, and a closed state wherein the relief valvesubstantially prevents fluid flow from the reservoir to the housinginterior.
 25. The tire inflation system of claim 1, wherein theeccentric mass comprises a first and a second piece, the eccentric massoperable between: a pumping mode wherein the first piece is adjacent thesecond piece; and a non-pumping mode wherein the first piece is distalthe second piece.
 26. A two-stage passive pump, comprising: a drivemechanism comprising a rotational axis, the drive mechanism comprising:a) a cam comprising an arcuate bearing surface having non-uniformcurvature, the cam coaxial with the rotational axis; and b) a masscouple to the cam that offsets a center of mass of the drive mechanismfrom the rotational axis; a first pump cavity cooperatively defined by:a) a first chamber having a first inlet and a first outlet; and b) afirst actuating element that forms a fluid seal with an open side of thefirst chamber, the first actuating element having a first actuatingarea; a second pump cavity cooperatively defined by: a) a second chamberhaving a second inlet and a second outlet; and b) a second actuatingelement that forms a fluid seal with an open side of the second chamber,the second actuating element having a second actuating area larger thanthe first actuating area; a first roller in non-slip contact with thecam and coupled to the first and second actuating elements, the firstroller comprising a first rotational axis having an arcuate positionthat is fixed relative to the first pump cavity; and a fluid manifoldfluidly connecting the second outlet to the first inlet.
 27. Thetwo-stage passive pump of claim 26, wherein the cam, first pump cavity,and second pump cavity share a common plane, wherein the first andsecond roller translate in a radial direction from the rotational axis.28. The two-stage passive pump of claim 26, further comprising: a secondfluid manifold fluidly connecting a reservoir to the first and secondpump cavities, wherein the reservoir is fluidly connected to the firstoutlet; a valve located within the second fluid manifold operablebetween: a open configuration in response to a reservoir pressureexceeding an opening threshold pressure of the valve, wherein the valvepermits fluid flow from the reservoir to the first and second pumpcavities; and a closed configuration in response to the reservoirpressure falling below a closing threshold pressure, wherein the valveprevents fluid flow from the reservoir to the first and second pumpcavities.
 29. The two-stage passive pump of claim 28, further comprisinga frame statically coupling the first roller to the second actuatingelement.
 30. The two-stage passive pump of claim 29, wherein the framecomprises a frame center, wherein the frame center is located in a firstradial position when the valve is in the closed configuration and in asecond radial position when the valve is in the open configuration,wherein the first radial position is different from the second radialposition.